Introduction. Vitamin D deficiency has been linked to an increased risk of asthma exacerbations. Objective. This study aimed to compare vitamin D status during the period of severe asthma exacerbations and investigate if vitamin D supplementation improves asthma control. Methods. A total of 47 asthmatic patients and 40 healthy subjects participated in this study. Serum 25-hydroxyvitamin D (25(OH)D), asthma control test (ACT) score, and % predicted peak expiratory flow rate were evaluated in the period with and without severe asthma exacerbations. After that, we provided vitamin D2 supplements to the patients with low vitamin D levels for 3 months. Results. At the period of asthma exacerbation, the prevalence of vitamin D deficiency and insufficiency was 38.29% and 34.04%. There was no significant difference in the levels of serum 25(OH)D with and without asthma exacerbations but the levels were significantly higher in the healthy group. Serum 25(OH)D levels significantly correlated with ACT score. Moreover, vitamin D2 supplementation improved asthma control in uncontrolled asthma group. Conclusions. Hypovitaminosis D was common in asthmatic patients but was not the leading cause of asthma exacerbations. Serum 25(OH)D levels correlated with the ability to control asthma. Improving vitamin D status might be a benefit in uncontrolled asthmatic patients.

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To address inborn errors of immunity (IEI) which were underdiagnosed in resource-limited regions, our centre developed and offered free genetic testing for the most common IEI by Sanger sequencing (SS) since 2001. With the establishment of The Asian Primary Immunodeficiency (APID) Network in 2009, the awareness and definitive diagnosis of IEI were further improved with collaboration among centres caring for IEI patients from East and Southeast Asia. We also started to use whole exome sequencing (WES) for undiagnosed cases and further extended our collaboration with centres from South Asia and Africa. With the increased use of Next Generation Sequencing (NGS), we have shifted our diagnostic practice from SS to WES. However, SS was still one of the key diagnostic tools for IEI for the past two decades. Our centre has performed 2,024 IEI SS genetic tests, with in-house protocol designed specifically for 84 genes, in 1,376 patients with 744 identified to have disease-causing mutations (54.1%). The high diagnostic rate after just one round of targeted gene SS for each of the 5 common IEI (X-linked agammaglobulinemia (XLA) 77.4%, Wiskott–Aldrich syndrome (WAS) 69.2%, X-linked chronic granulomatous disease (XCGD) 59.5%, X-linked severe combined immunodeficiency (XSCID) 51.1%, and X-linked hyper-IgM syndrome (HIGM1) 58.1%) demonstrated targeted gene SS should remain the first-tier genetic test for the 5 common X-linked IEI.

RATIONALE: CRTH2(CD294) is the target in allergies treatment due to its expression in various cell types. The rational of CRTH2 expression on T helper cells (Th,CD3 + CD4 +), regulatory T cells (Treg, CD3 + CD4 + CD25 + CD127-) and cytotoxic T cells(Tc,CD3 + CD8 +) in asthma patients remains unclear. We assessed CRTH2 expression level in T cell subsets in correlation with clinical data. METHODS: The CRTH2 expression on T cells in whole blood were analyzed using flow cytometry. %predicted PEFR, asthma control test(ACT), asthma quality of life questionnaire and absolute eosinophil counts were investigated to find the correlation with CRTH2 expression level. RESULTS: 46 asthma patients(11 eosinophilic asthma patients, 30 noneosinophilic allergic asthma patients, and 5 non-eosinophilic non-allergic asthma patients) and 11 healthy subjects were enrolled. Asthma patients had higher level of CRTH2 + Treg cells of total CD3 + cells(0.12%60.09 and 0.04%60.03, p50.001) and higher frequency of CRTH2 expression on Tc than healthy(1.04%60.51 and 0.60%60.50, p50.006). No significant difference of CRTH2 expression on Th cells was observed. In subgroup analysis, we found the frequency of CRTH2 expression on Treg cells in eosinophilic asthma patients (0.19%60.14) was significantly higher than non-eosinophilic allergic asthma patients(0.10%60.06) and non-eosinophilic non-allergic asthma patients(0.06%60.03). The frequency of CRTH2 expression on Treg cells among asthma patients had negative correlation with ACT scores(r5-0.29, p50.04) whereas positive correlation with absolute eosinophil counts(r50.39, p50.007). CONCLUSIONS: Elevated levels of peripheral CRTH2 expression on Treg and Tc cells are key features in asthma. The different correlation of CRTH2 + Treg cells with asthma control and eosinophil counts elucidated as potential targeted therapy for future asthmatic treatment.

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